Tracking App Download Sources in Google Analytics

I have an App which is for Android as well as IOS, in Google Analytics I have selected App while creating the account and added SDK 2 on the app code.

But the problem is that in the analytics account I do not see any data related to download sources. Acquisitions >> Google Play >> Sources shows Source/Medium as "(direct) / (none)"

My goal was to track sources for the downloads as suppose a visitor clicks a link to the app on Facebook and downloads the app then I should be able to see Facebook as the source in this section = Acquisitions >> Google Play >> Sources